Inching device for switch jaw



Aug. 2, 1955 D, R, JAMISQN 2,714,646

INCHING DEVICE FOR SWITCH JAW Filed Sept. 14, 1953 2 Sheets-Sheet l yINVENTOR.

Aug. 2, 1955 D. R. JAMISON 2,714,646

INCHING DEVICE FOR SWITCH JAW Fil-ed Sept. 14, 1953 2 Sheets-Sheet 2INVENTOR.

. A v hm/Jaw o dk K T United States Patent fiice Patented Aug. 2, 1:95.:

2,714,646 IN CHIN G DEVICE FOR SWITCH JAW Donald Ray Jamison,Greensburg, Pa., assignor to I-T-E Circuit Breaker Company,Philadelphia, Pa., a corporation of Pennsylvania Application September14, 1953, Serial No. 380,046 4 Claims. (Cl. 200-462) My presentinvention relates to a safety device for hookstick operated switches andis more particularly directed to a device which permits the opening of adisconnect switch by a hook stick only a small amount during the initialopening operation and thereafter permits the disconnect switch blade tobe fully opened by the operator if he observes no arc during the initialopening operation.

My invention is particularly directed to disconnect switches of a highvoltage hook-stick operated type. In switches of this type, one or moreblades, usually rectangular in cross section and having one end attachedto a hinged terminal, are rotated about the hinged terminal into and outof engagement with a break jaw to close and open the switch. Thisoperation is usually accomplished from a remote point by means of aninsulated hook stick which engages pull ring at the break end of theblade.

When this type of switch is opened by means of an insulated switch stickor hook stick, it is impossible to open it a short distance and close itagain, since considerable effort is required to pull the blade out ofthe jaw. However, as is well known in the art, disconnect switches serveprimarily to sectionalize electrical circuits and are not designed toopen or interrupt the circuit when there is a current flowing therein.

Thus, it is essential, in order to protect the switch and circuit, thatthe disconnect switch be opened only under no load conditions.

However, due to the frictional engagement between the switch blade andthe jaw end as a result of the dimensions and mass of the switch blade,it is relatively impossible to open the blade only a short distance.That is, since the magnitude .of effort or force required to initiallyseparate thecooperating contacts is so great, it is impossible for theoperator to only open the blade a short distance.

Hence, it is possible that due to an operators mistake or for some otherreason, a disconnect switch may be completely opened under loadconditions. Such faulty operation can result in total destruction of thedisconnect switch and in considerable harm or even death to the,operator. That is, a relatively heavy pull is required on the hook stickring or pull ring to disengage the blade on the jaw contact. Whereas,thereafter, a relatively light pull will move the switch to the fullopen position, the natural resuit, is that when the necessaryheavy pullis applied to disengage the Switchblade, the switch will immediatelymove rapidly to the full open position whether or not there is currentflowing inits circuit.

. In disconnect switches other than hook sticks which do not require theinitial heavy pull of a hook stick to separate the cooperating contacts,faulty operation of the device can be eliminated by instructing theswitch operator to first open the disconnect switch by a very smallamount and if an arc is drawn, to, immediately reclose the switch.

However, the main shortcoming of this scheme is that, as above noted, itis impossible, in most hook stick operated disconnect switches toseparate the contacts a short distance due to the relatively large pullthat is required to initially separate the cooperating contacts.

i: ll

stationary part and a spring.

Many units of the prior art have been developed to provide a safetydevice for opening disconnect switches that renders it impossible forthe operator to fully open the switch without first observing whether ornot current is flowing in a circuit.

With these prior art devices, added to the switch blade, it isautomatically stopped when it is opened far enough to cause an are butnot far enough to initiate an are over to ground or between phases. Theoperator will be able to observe the small arc and be able to reclosethe switch thereby preventing an interruption of service or destructionto the switch.

Thus, with this arrangement, the possibility of drawing an are anappreciable length is eliminated and hence there will be no subsequentfault or short circuit to destroy the switch. That is, an arc with thisattachment is of such short length that it is usually not sufiicient tocause a flashover to ground or cross phase.

However, the safety or inching devices of the prior art prevent theopening of the disconnect switch unload and are usually applied to thehinge end of the disconnect switch and not to the blade end as set forthin my invention.

A representative example of the type of prior art inching device appliedto the hinge end is disclosed in U. S. Patent 1,933,285, issued October31, 1933.

However, this type of arrangement has many disadvantages, for example,when the inching device is on the hinge end of the blade, it must beclose to the hinge so that it the device is much shorter than thedistance from the hinge to the, pull ring which is located at the bladeend of the aw.

Thus, with this arrangement, the operator would be able to bend ordamage the blade. By providing the inching device at the hinge end, itmust be mounted so close to the pivot point that the mechanicaladvantage is very unfavorable.

Hence, a pull of 100 lbs. at the pull ring might result in a pull of1,000 or 2,000 lbs. at the inching device. On the other hand, in mynovel arrangement, wherein the inching device is mounted at the jaw endof the switch, a mechanical advantage of l to 1.5 is obtained so that itis much less likely to fail.

Furthermore, with the inching device positioned at the hinge end of theblade, additional manufacturing diificuities are encountered.

In order to provide proper protection for the circuit it is essentialthat the are drawn during the initial opening operation be a very shortlength. Thus the blade must stop just clear of the jaw, approximately ofan inch. The blade moves only a short distance.

Since the distance from the jaw to the hinge is much greater than thedistance from the inching device to the hinge, it is extremely difficultto design the device and manufacture one which will be accurate enoughto stop the blade in the proper position.

My novel device is comprised of a movable part, a

This device is permanently secured to the break or jaw end of a hookstick operated disconnected switch in such a manner that the disconnectswitch can be completely opened only after it has been opened by a smallamount, thus permitting the operator to notice whether an arc has beendrawn and if an arc is drawn to move the disconnect switch blade back tothe closed position or if no arc is drawn to cornpletely open thedisconnect switch.

The safety or inching device of my invention consists essentially of abase (stationary part), resilient spring and latch (movable part), whichare mounted at the jaw end of the disconnect switch. The pivot pin ofthe pull ring or any other latch p'in extending from the switch bladeengages the latch portion of the inching device when the switch isinitially opened. The resilient member is rigidly secured at one end tothe base and the latch member is slidably mounted on the base. When thelatch is in a first position, the resilient member applies a force tothe latch on one side of its pivot point to prevent its counterclockwiserotation. However, when the latch is moved to its second position,thereby changing its pivot point, the resilient member applies a forceon the other side of the pivot thereby causing counterclockwise rotationthereof.

In the switch closed position, the inching device latch is engaged bythe latch pin which is attached to the rotating blade of the disconnectswitch. In this position, the resilient member applies a force above thepivot of the latch thereby preventing counterclockwise rotation thereof.As the switch is initially moved toward the open position, the switchblade latch pin comes into contact with the inching device latch therebycausing it to move upward due to its slidable mounting on the base ofthe inching device to thereby change its pivot point.

in this second step, the blade latch pin is hooked by the inching devicelatch and hence even though the force of the resilient member is nowexerted below the pivot point of the latch, the hook engagement willprevent counterclockwise rotation thereof. While the components are heldin this position, the blade is slightly separated from the jaw andhence, the operator can readily ascertain whether or not an attempt isbeing made to open a switch on an energized circuit. That is, if theline being interrupted is not dead, a spark or arc will exist betweenthe blade and the jaw to indicate to the operator that the switch shouldnot be opened. However, if no sparking or arcing exists between theblade and the jaw while the unit is held in this second position, theoperator can relax the force on the hook stick which will remove thehook engagement between the inching device and the blade latch pin.

Since the latch has been moved to its second position, the resilientmember will bias same in a counterclockwise direction and thus therelease of the hook engagement will result in counterclockwise rotationof the inching device latch. This movement automatically removes theobstacle in the opening path movement in the switch blade and hence theoperator can now pull the blade to its full open position. That is, whenthe operator has ascertained the correctness of the operation, it isonly necessary for him to move the blade slightly in the oppositedirection to permit disengagement of the inching device latch from theblade latch pin so that the operator can now move the blade to its fullopen position.

During the closing operation, the blade latch pin engages a secondextension of the inching device latch thereby slidably moving same fromits second pivot to its first pivot point. Thus, the inching device isautomatically moved to its reset position on the manual reclosing of thedisconnect switch to thereby render it effective as a safety device on asubsequent opening operation.

Accordingly, a primary object of my invention is to provide a novelsafety device or inching device which may be secured to the break or jawend of a hook stick operated disconnect switch to protect the circuit,the disconnect switch and the spring from faulty operation of thedisconnect switch and provides a mechanical advantage so that the springwill not bend or damage the blade when it is initially stopped duringthe opening operation.

Still another object of my invention is to provide an inching devicewhich will be engaged by the switch blade near the jaw end so that theconstruction and dies do not have to be accurate and, in addition, needsno means for adjustment in order to maintain and hold the proper spacingbetween the jaw and the blade.

Still another object of my invention is to provide an inching devicewhich can be operated on the break or jaw end of a hook stick operateddisconnect switch without blade dismantling or making any alterations ofthe disconnect switch.

A still further object of my invention is to provide a safety or inchingdevice which will not prevent the closing of the switch blade in theevent the device is moved while the switch blade is in the fully openedposition.

Another object of my invention is to provide a novel inching devicepermanently mounted at the jaw end of a hook stick operated disconnectswitch which will permit operation of the switch to appraise theoperator of the line being interrupted prior to the complete opening ofthe switch.

A still further object of my invention is to provide a novel safetydevice which will prevent the manual operation of the disconnect switchfrom the fully closed to the fully opened position by a singleoperation, thereby compelling the operator to take cognizance of thecondition of the line prior to moving the blade to the full openposition.

A still further object of my invention is the provision of inching meansat the jaw end of the blade whereby the disconnect switch can be fullyopened only after a previous trial opening to ascertain whether thedisconnect switch is being opened under load or not.

Still another object of my invention is the provision of means whereby adisconnect switch, during its opening operation, must first be opened bya small amount and if the operation is found to be correct cansubsequently be moved to its fully opened position.

Still another object of my invention is to provide an inching device atthe jaw end of a hook stick operated disconnect switch that is easilyapplied to standard type switches for all voltage ratings.

Another object of my invention is to provide an inching device which hasonly three basic components, is relatively inexpensive and due to itssimplicity cannot be rendered inoperative.

These and other objects of my present invention will be apparent fromthe following description when taken in connection with the drawings inwhich:

Figure 1 is a side view of a typical hook stick operated disconnectswitch to which my invention can be applied. This figure illustrates themanner in which my inching device is secured at the jaw end and showsthe various components when the switch is in the completely closedposition.

Figure 2 is a side view similar to Figure 1 and illustrates the positionof the various parts when the switch is in the partially open position.This figure illustrates the manner in which the novel inching devicepermits only a small initial movement of the disconnect switch blade.

Figure 3 is a side view similar to Figures 1 and 2 and illustrates theposition of the various parts following the initial opening operation.This figure illustrates the position of the novel inching device topermit the blade to be moved to its fully opened position.

Figure 4 is a perspective view of my novel inching device.

Referring now to Figure 1, the disconnect switch shown may be of anytype well-known in the art. The switch illustrated is similar to thatset forth in copending application Serial No. 315,619, filed October 20,1952.

Although the disconnect switch per se forms no part of my presentinvention, a brief description thereof is included to facilitate theunderstanding and operation of my novel inching device incorporatedtherewith.

The insulator units 10 and 11 are mounted on the base 12 in anydesirable manner. The upper end of the insulator units 10 and 11 supportthe terminals 14 and 15 which are attached thereto by means of bolts 17and 18. The terminals members 14 and 15 are each provided with ahorizontal extension 16 and 16', respectively, which have appropriatemeans to permit connection to the electrical line in which thedisconnect switch is connected. The vertical extension 19 of theterminal connector 14 has the hinged end of the contact blades 30, 31rotatably mounted thereon by means of pin 32. The terminal connector 15located at the jaw. end of the disconnect switch is provided with avertical extension 40 which forms the break tongue of the disconnectswitch.

It will be noted that the disconnect switch has contact blades and 31which straddle the tongue when the switch is in closed position as seenin Figure 1. At the jaw end of the blades an opening is provided toreceive a screw-nut arrangement which serves the triple purposes of;

1. Providing a mounting and pivot for the pull ring 80;

2. Providesa force on the spring washers 110 to thereby urge the blades30-31 against the jaw 40 when the switch is in the closed position and3. Serves as a latch pin for cooperation with the latch 103 of theinching device, as will hereinafter be more fully described.

The inching device of my invention comprises the base unit 101,resilient member 102 and latch member 103. The base member 101 isrigidly secured by any appro priate means such as bolts 104, 105 at thejaw end of the disconnect switch. The vertical extending member 106 ofthe base 100 has a vertical slot 107, as best seen in the cut away viewof Figure 4. The latch member 103 is comprised of two parallel spacedsections 110 and 111 which straddle the vertical extension 106 of thebase. A pin 108 rigidly secured to the parallel section 110, 111 isseated in the vertical slot 107 to thereby provide a slidable mountingof latch member 103 on base member 101. The lower portion of theparallel spaced sections 110, 111 have a protruding section 113 whichmay be joined together by welding, rivet or pin 114. The upper portionof the parallel member 110, 111 have an insulating hook or latch 116secured therebetween by means of the rivets or pin 117.

When the disconnect switch is in the closed position of Figure 1 so thatthe blades 30-31 straddle between the break tongue 40, the blade latchpin 100 will be resting on the protruding portion 113 of the latchmember 103, as seen in Figure l. The resilient member 102 is rigidlymounted at its lower end to the base 101 by means of screw 120. Theupper free end of the resilient spring 102 has a V-shaped section 121which is resiliently urged against the latch member 103. When the switchis in the closed position, the blade latch pin 100 will urge the latchmember 103 to its lowermost position so that the pin 108 isat the bottomof the vertical slot 103. In

this position, the force exerted by the V-section 121 of the resilientmember 102 on the latch member 103 will be above the pivot 108 thereof.Hence, the bias on the latch member 103 will be in a counterclockwisedirection, but due to the protruding joined sections 113 of the spacedparallel sections 110, 111, the latch member 103 will be prevented fromhaving counterclockwise rotation.

When the operator desires to open the switch, the end of a hook stick isinserted in the ring 80 and the switch blade 30 is moved upwardly.During this initial movement, the blade latch pin 100 will be broughtinto engagement with the insulating latch or hook 116 of the latchmember 113. The insulation material extends a short distance beyond themetal side pieces 110-111 so as to make contact with latch pin 100 whenthe switch is partially open, (Figure 3). Hence, there will not be aconducting path through the inching device when the switch is partiallyopen. Since the force exerted through the pull ring 80 will rotate theblades 30-31 around its hinge end 32, upward force will be exerted onthe latch member 103. Hence, this unit will moved from its lowermostposition of Figure 1 to its uppermost position of Figure 2. That is, thepin 108 will be moved from the lower end of the slot 107 to the upperend thereof. In this first disengaged position of blade 30, the movablepivot 108 of the latch member 103 will be above the V-section 121 of theresilient member 102 and hence the bias exerted on the latch member 103will be in a counterclockwise direction. However, the latch member 103will be prevented from moving in this clockwise direction due to thehook engagement between the latch 116 and the blade latch pin 100.Therefore, even though the operator is exerting a continuous openingforce on the switch blades 30-31, the latch member 103 will present anobstacle through its continued movement and the blade 30-31 cannot bemoved to its full open position. However, in the partial open positionindicated in Figure 2, there is a slight separation of approximately /8of an inch between the switch blades 39-31 and its cooperatingstationary contacts comprising the break tongue 40.

If operator has attempted to open the disconnect switch on a live line,the spark or gap existing in the area will immediately appraise him ofthe condition of the line and hence he can now move the switch blade 30back to the closed position of Figure 1. That is, when the blade 30 ismoved to its engaged position, the blade latch pin 100 will reengage theprotrusion 113 and thereby move the latch member 103 back to its initialposition so that the biasing force thereon is now changed to acounterclockwise direction. However, if no spark or are exists betweenthe blade 30 and members 40, 41 at the area 130, the operator will beinsured of the fact that the switch is being opened on a dead line andhence, full opening operation of the switch will not result in adangerous condition to either the equipment or the operator.

To remove the barrier created by the latch member 103, the operator needonly move the switch blade 30 for a short distance in the oppositedirection to the second disengaged position. This will remove the hookengagement between the latch 116 and the blade latch pin 100.

Since the latch member 103 is pivoted about the upper portion of theslot 107, the V-section 121 of the resilient member 102 will rotate thelatch member 103 in a clockwise direction.

It will be noted that the vertical extension 106 of the base 100 isprovided with a cut away portion 131 to receive the V-section 121 of theresilient: member 102 when the latch member 103 is rotated in aclockwise direction.

The upper portion 132 comprising one leg of the V 121 of the resilientmember 102 is at an angle and'will limit the extreme clockwise rotationof the latch member 103 when its back surface is parallel to and inengagement with the portion 132, as seen in Figure 3. Thus, after thelatch member 103 has been rotated to its extreme clockwise position, theoperator may then again exert an opening force on the switch blade 30through the pull ring 80 to thereby move it to the full opened or 3rddisengaged indicated in Figure 3.

Thus, it will be noted that this disconnect switch can be openedcompletely only after it has been opened by a small amount to therebyenable the operator to notice whether or not an arc has been drawn. Ifan arc has been drawn, the operator may then move the operating switchblade back to its engaged position. In the event no arc has been drawn,the operator may then subsequently completely open the switch to itsfull opened position.

When the switch blade 30 is moved from the full opened position ofFigure 3 to the completely closed position of Figure 1, the sequence ofoperation is indicated respectively in Figures 3, 2 and 1. Thecomponents follow the reverse operation heretofore described inconnection with the opening operation. That is, the switch blades 30-31are moved towards its closed position and the engagement of the bladelatch pin 100 with the protrusion 113 will initially rotate the latchmember 103 against the biasing force of the resilient member 102 andalso move this member from its extreme upward position of Figure 2 toits extreme lower position of Figure 1. Thus, all of the components willbe reset in their initial position and the inching device wil. beefiective as a safety means for a subsequent opening operation.

It will be noted that in the event the latch member 103 is moved fromthe position of Figure 3 to the position of Figure l or 2 when thedisconnect switch blade 30-31 are in the fully opened position that theoperator can nevertheless move the blades 30--31 from the fully openposition of Figure 3 to the fully closed position of Figure 1.

During the closing operation, the latch pin 100 will engage the upperportion of the insulating surface 116 and the closing force on theswitch blade will cause the latch member 103 to rotate clockwise,thereby removing itself as an obstacle to the movement of the bladesfrom the fully opened to the fully closed position. Thus, in some rate,it will be noted that I have provided a novel inching device which canbe operated at the blade and at a hook stick operated disconnect switchwhich due to its novel construction and positioning, provides safetyoperation of of bending or damage to the blade when the operator exertsa large force by means of a hook stick through the pull ring toinitially separate the cooperating contacts.

In the foregoing, I have described my invention only in connection withpreferred embodiments thereof. Many variations and modifications of theprinciples of my invention within the scope of the description hereinare obvious. Accordingly, I prefer to be bound not by the specificdisclosure herein but only by the appending claims.

I claim:

1. In a switch having a blade, a hinge end and a jaw end; said bladerotatably mounted on said hinge end of said switch; said blade having anengaged and a first, second and third disengaged position with respectto said jaw end; a safety device comprising a base member, a resilientmember and a latch member; said safety device mounted at said jaw end ofsaid switch; said latch member slidably mounted on said base member;said resilient member secured to said base member; said resilient memberbiasing said latch member in a first direction when said blade is insaid engaged position; said resilient member biasing said latch memberin a second direction when said blade is in said first, second and thirddisengaged position.

2. In a switch end; said blade rotatably mounted on said hinge end ofsaid switch; said blade having an engaged and a first, second and thirddisengaged position with respect to said jaw end; a safety devicecomprising a base member, a

the switch and still prevents the possibility having a blade, a hingeend and a jaw 7 resilient member and a latch member; said safety devicemounted at said jaw end of said switch; said latch member slidablymounted on said base member; said resilient member secured to said basemember; said resilient member biasing said latch member in a firstdirection when said blade is in said engaged position; said resilientmember biasing said latch member in a second direction when said bladeis in said first, second and third disengaged position; said latchmember having a first pivot point when said blade is in said engagedposition; said latch member having a second pivot position when saidblade is in said first, second and third disengaged point.

3. In a switch having a blade, a hinge end and a jaw end; said bladerotatably mounted on said hinge end of said switch; said blade having anengaged and a first, second and third disengaged position with respectto said jaw end; a safety device comprising a base member, a resilientmember and a latch member; said safety device mounted at said jaw end ofsaid switch; said latch member slidably mounted on said base member;said resilient member secured to said base member; said latch memberhaving a first and second position with respect to said base member;said switch blade eflective to maintain said latch member in said firstposition when said switch blade is in said engaged position; said switchblade effective to move said latch member to said second position whensaid blade is moved to said first disengaged position; said resilientmember eifective to bias said latch member in a first and seconddirection; said resilient member rendered effective when said latchmember is in said first position to bias said latch in said firstdirection; said resilient member ineffective to move said latch memberin said second direction when said'blade is in said first disengagedposition; said resilent member effective to move said latch member insaid second direction when said blade is in said second and thirddisengaged position.

4. In a switch having a blade, a hinge end and a jaw end; said bladerotatably mounted on said hinge end of,

said switch; said blade having an engaged and a first, second and thirddisengaged position with respect to said jaw end; a safety device havinga base member, a latch member and a resilient member; said base memberrigidly secured at said jaw end of said switch; said latch memberslidably mounted on said base member; said blade effective to maintainsaid latch member in a first position when said blade is in said engagedposition; said resilient member efiective to rotate said latch member ina first direction when said blade is in said engaged position; saidblade efiective to maintain said latch member in a second position whensaid blade is in said first disengaged position; said resilient membereflective to rotate said latch member in a first direction when saidblade is in said second and third disengaged position.

References Cited in the file of this patent UNITED STATES PATENTS1,669,125 Hartmann May 8, 1928 1,933,285 Strai Oct. 31, 1933 2,420,166Corey et a1 May 6, 1947

